SwiftUI co-creator defends client-side animations: dropping Core Animation was deliberate
JordanMorgan10 · x · 2026-09-16
- A SwiftUI co-creator (also one of Core Animation's creators) responds to criticism that SwiftUI animations feel janky because they bypass Core Animation. Running animations in the app process instead of the render server was one of the earliest, most fundamental design decisions.
- Signature iPhone experiences like UIScrollView rubber-banding and SpringBoard app switching are only possible as client-side animations, since interruptible, interactive animation must share the process with event handling — hard to build in UIKit.
- iOS 18 added new AppKit/UIKit APIs to adopt the SwiftUI client-side animation model. He concedes SwiftUI has many valid critiques, but not using Core Animation isn't one.
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